/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Runtime.Serialization;
using Spring.Reflection.Dynamic;

namespace Spring.Expressions;

/// <summary>
/// Represents parsed function node.
/// </summary>
/// <author>Aleksandar Seovic</author>
[Serializable]
public class FunctionNode : NodeWithArguments
{
    /// <summary>
    /// Create a new instance
    /// </summary>
    public FunctionNode()
    {
    }

    /// <summary>
    /// Create a new instance from SerializationInfo
    /// </summary>
    protected FunctionNode(SerializationInfo info, StreamingContext context)
        : base(info, context)
    {
    }

    /// <summary>
    /// Evaluates function represented by this node.
    /// </summary>
    /// <param name="context">Context to evaluate expressions against.</param>
    /// <param name="evalContext">Current expression evaluation context.</param>
    /// <returns>Result of the function evaluation.</returns>
    protected override object Get(object context, EvaluationContext evalContext)
    {
        string name = this.getText();

        object[] argValues = ResolveArguments(evalContext);

        object function = evalContext.Variables[name];

        // delegate?
        Delegate callback = function as Delegate;
        if (callback != null)
        {
            return InvokeDelegate(callback, argValues);
        }

        // lambda?
        LambdaExpressionNode lambda = function as LambdaExpressionNode;
        if (lambda != null)
        {
            try
            {
                return GetValueWithArguments(lambda, context, evalContext, argValues);
            }
            catch (ArgumentMismatchException ame)
            {
                throw new InvalidOperationException("Failed executing function " + name + ": " + ame.Message);
            }
        }

        if (function == null)
        {
            throw new InvalidOperationException("Function '" + name + "' is not defined.");
        }

        throw new InvalidOperationException("Function '" + name + "' is defined but of unknown type.");
    }

    private object InvokeDelegate(Delegate callback, object[] arguments)
    {
        return new SafeMethod(callback.Method).Invoke(callback.Target, arguments);
    }
}
